Process for the preparation of 3-hydroxymethyl-6-chlorobenzoxazolone

ABSTRACT

Process for the preparation of optionally hydroxymethylated 6-chlorobenzoxazolone, which consists in chlorinating and, if appropriate, hydroxymethylating benzoxazolone in a mixture of water and dioxane.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of application Ser. No. 242,538, filedMar. 11, 1981, now U.S. Pat. No. 4,435,557.

The present invention relates to a process for the preparation ofchlorinated derivatives of benzoxazolone, which can be used, inparticular, as intermediates in the preparation of insecticides.

More precisely, the invention relates to the preparation of derivativesof the 6-chlorobenzoxazolone type of the formula ##STR1## in which Arepresents a hydrogen atom or a hydroxymethyl group.

One object of the invention is to make it possible to obtain derivativesof the formula (I) with good yields using benzoxalone as the startingmaterial or reactant.

Benzoxazolone is understood as meaning the product of the formula##STR2##

This product is sometimes referred to as benzoxazolinone, especially inthe English language.

Another object of the invention is to make it possible to use moistbenzoxazolone, which is a form of benzoxazolone obtained convenientlyand economically on an industrial scale.

Russian Pat. No. 245,111 has already described the chlorination ofbenzoxazolone in chlorinated alkanes or alkenes, such astetrachloroethane.

It is also known that benzoxazolone is converted to3-hydroxymethylbenzoxazolone by reaction with formaldehyde in aqueoussolution [Zinner et al., Ber., 89, 2,135 (1956)].

However, these various processes are not satisfactory for variousreasons related, in particular, to the purity of the products obtainedor to the limited degree of conversion of the reaction.

One object of the invention is to provide a process for the preparationof derivatives of the formula (I) which does not have the disadvantagesof the known processes.

Another object of the invention is to provide a process for thepreparation of derivatives of the formula (I) which, as far as possible,avoids the formation of abnormally chlorinated products, such as thederivatives polychlorinated on the aromatic nucleus.

Another object of the invention is to facilitate the separation and thepurification of the products of the formula (I) obtained at the end ofthe reaction.

Another object of the invention is to provide a process for thepreparation of products of the formula (I) which makes it possible, atthe end of the reaction, easily to recover the solvents which may havebeen used during the reaction.

Another object of the invention is to provide a means of convenientlylinking various operations necessary for obtaining certain intermediatesfor the preparation of phosalone.

It has now been found that these objects can be achieved by virtue ofthe process forming the subject of the present invention.

This process according to the invention comprises reacting benzoxazolonewith chlorine in the presence of water and dioxane.

The mixture of water+dioxane used in the process of the inventiongenerally comprises between 20 and 80% by weight of dioxane andpreferably more than 50% of dioxane.

The amount of benzoxazolone used in the reaction is generally between 50and 500 g/liter (grams per liter of reaction mixture) and preferablybetween 150 g/liter and 400 g/liter.

The chlorine is generally added by gradual introduction into thereaction medium, where it dissolves and/or reacts rapidly; the reactiontime can vary very widely, but, for economic reasons, it is generallybetween 1 hour and 15 hours and preferably between 2 and 10 hours.

The reaction temperature is generally between -20° C. and +90° C. andpreferably between 40° and 80° C.

The main reaction product obtained in accordance with the process whichhas now been described is 6-chlorobenzoxazolone of the formula ##STR3##

The reaction is advantageously continued until a maximum yield of6-chlorobenzoxazolone has been obtained; the course of the reaction canbe followed by any means which is in itself known, e.g. potentiometry.The presence of an aqueous reaction medium is advantageous for the veryreason that it makes it possible conveniently to follow the course ofthe reaction by potentiometry.

It is also possible to adapt the amount of chlorine added so as toobtain this maximum yield of 6-chlorobenzoxazolone. The amount ofchlorine added is advantageously close to the stoichiometric amount; itis generally between 1 and 1.1 mols/mol (i.e. mols of chlorine per molof benzoxazolone used) and preferably between 1.03 and 1.07 mols/mol.

Hydrogen chloride is formed during the reaction and dissolves at leastpartially in the reaction medium, but can also be evolved in the gaseousstate.

At the end of the reaction, the reaction mixture is advantageouslyneutralized with a basic agent, e.g. a hydroxide or carbonate of analkali metal or alkaline earth metal, preferably of sodium or potassium.

Very frequently, the presence of the different reaction andneutralization products causes salting out, i.e. separation of thereaction medium into two liquid phases, the one being essentiallyorganic and the other essentially aqueous.

According to a first variant of the invention, the 6-chlorobenzoxazoloneis isolated from the reaction medium by any means which is in itselfknown, e.g. by crystallization.

According to a convenient embodiment of the invention, the yield and thepurity of the 6-chlorobenzoxazolone obtained can be adjusted bymodifying the conditions of crystallization, in particular thewater/dioxane ratio and the temperature during this crystallization andthe subsequent filtration.

According to another variant of the process of the invention, the6-chlorobenzoxazolone is reacted with formaldehyde to form3-hydroxymethyl-6-chlorobenzoxazolone, or in other words the product ofthe formula (I) in which A represents a hydroxymethyl radical. Accordingto an especially advantageous embodiment, the 6-chlorobenzoxazolone isused in the form of the organic layer obtained at the end of theprevious reaction, which makes it possible to avoid any crystallizationor other form of isolation of the 6-chlorobenzoxazolone.

The formaldehyde used can be in the form of paraformaldehyde or moresimply in the form of an aqueous solution (formol).

The reaction is carried out at between 20° and 100° C. and preferablybetween 60° and 90° C.; the formaldehyde is advantageously used inexcess, relative to the 6-chlorobenzoxazolone. The molar ratio ##EQU1##is generally between 0.8 and 2 and preferably between 1 and 1.3.

The concentration of 6-chlorobenzoxazolone used in the reaction iswithin the same limits as those indicated for the benzoxazolone in theprevious reaction step; the same applies to the water/dioxane ratio.

At the end of the reaction, the 3-hydroxymethyl-6-chlorobenzoxazolone isisolated by any means which is in itself known, e.g. by crystallization.As in the previous step, it is possible to adjust the yield and thedegree of purity of the 3-hydroxymethyl-6-chlorobenzoxazolone bymodifying the water/dioxane ratio and the temperature at which thecrystallization/filtration operations are carried out.

The 3-hydroxymethyl-6-chlorobenzoxazlone can be converted to3-chloromethyl-6-chlorobenzoxazolone with the aid of known chlorinatingagents (PCl₃, SOCl₂ and the like), and the3-chloromethyl-6-chlorobenzoxazolone can itself be used to produceinsecticidal products (phosalone) in accordance with known processes.

The following examples, which are given without implying a limitation,illustrate the invention and show how it can be put into effect.

EXAMPLE 1

Water (335 g), dioxane (457 g) and benzoxazolone (270 g) are introducedinto a 2 liter reactor.

The medium is heated to a temperature of 40° C. and chlorine is injectedinto this medium at a rate of 10 liters/hour, by means of a glass tube,until an amount of 147 g has been absorbed by the reaction medium(reaction followed by potentiometry).

The reaction medium is neutralized with an aqueous sodium hydroxidesolution of 30% strength by weight (246 g). The temperature is thenraised to 85° C. and salting out takes place; the upper organic phase,which contains mainly dioxane and 6-chlorobenzoxazolone, is separatedoff by decantation. Water (250 g) is added thereto and the medium isheated to 80° C., which makes it homogeneous, and cooled to 20° C.,which causes the 6-chlorobenzoxazolone to crystallize. By filtration,the latter is obtained with a yield of 85.7% (relative to thebenzoxazolone used) and a degree of purity of 99%.

EXAMPLE 2

Example 1 is repeated up to the salting-out step. The organic phase isseparated off by decantation. A 30% strength by weight aqueous sodiumhydroxide solution (about 1 cc) is added to this organic phase so thatthe pH becomes equal to 4.5; an aqueous formaldehyde solution of 30%strength by weight (202 cc) is then added. The mixture is heated at 65°C. for half an hour.

At the end of the reaction, water (235 g) is added and the mixture iscooled, which causes the 3-hydroxymethyl-6-chlorobenzoxazolone tocrystallize, the latter thus being obtained with a yield of 83%(relative to the benzoxazolone initially used at the start of Example 1)and a degree of purity of 99.5%.

We claim:
 1. A process for the preparation of3-hydroxymethyl-6-chlorobenzoxazolone which comprises reacting6-chlorobenzoxazolone in organic solution with formaldehyde in thepresence of water and dioxane, the 6-chlorobenzoxazolone having beenprepared by reacting benzoxazolone with molecular chlorine in thepresence of water and dioxane wherein said organic solution being6-chlorobenzoxazolone and dioxane.
 2. A process according to claim 1,wherein the mixture of water and dioxane for each reaction comprisesbetween 20 and 80% of dioxane.
 3. A process according to claim 2,wherein the mixture of water and dioxane for each reaction comprisesmore than 50% of dioxane.
 4. A process according to claim 1, wherein theformaldehyde is in aqueous solution.
 5. A process according to claim 2,wherein the formaldehyde is in aqueous solution.
 6. A process accordingto claim 3, wherein the formaldehyde is in aqueous solution.
 7. Aprocess according to claim 1, wherein the molar ratio offormaldehyde/6-chlorobenzoxazolone is between 0.8 and
 2. 8. A processaccording to claim 2, wherein the molar ratio offormaldehyde/6-chlorobenzoxazolone is between 0.8 and
 2. 9. A processaccording to claim 4, wherein the molar ratio offormaldehyde/6-chlorobenzoxazolone is between 0.8 and
 2. 10. A processaccording to claim 7, wherein the molar ratio is between 1 and 1.3. 11.A process according to claim 8, wherein the molar ratio is between 1 and1.3.
 12. A process according to claim 9, wherein the molar ratio isbetween 1 and 1.3.
 13. A process according to claim 1, wherein theamount of 6-chlorobenzoxazolone used is between 50 and 500 g/liter ofreaction mixture and the reaction temperature is between 20° and 100° C.14. A process according to claim 2, wherein the amount of6-chlorobenzoxazolone used is between 50 and 500 g/liter of reactionmixture and the reaction temperature is between 20° and 100° C.
 15. Aprocess according to claim 4, wherein the amount of6-chlorobenzoxazolone used is between 50 and 500 g/liter of reactionmixture and the reaction temperature is between 20° and 100° C.
 16. Aprocess according to claim 7, wherein the amount of6-chlorobenzoxazolone used is between 50 and 500 g/liter of reactionmixture and the reaction temperature is between 20° and 100° C.
 17. Aprocess according to claim 10, wherein the amount of6-chlorobenzoxazolone used is between 50 and 500 g/liter of reactionmixture and the reaction temperature is between 20° and 100° C.
 18. Aprocess according to claim 13 wherein the amount of6-chlorobenzoxazolone used is between 150 and 400 g/liter and thereaction temperature is between 60° and 90° C.
 19. A process accordingto claim 14 wherein the amount of 6-chlorobenzoxazolone used is between150 and 400 g/liter and the reaction temperature is between 60° and 90°C.
 20. A process according to claim 15 wherein the amount of6-chlorobenzoxazolone used is between 150 and 400 g/liter and thereaction temperature is between 60° and 90° C.
 21. A process accordingto claim 16 wherein the amount of 6-chlorobenzoxazolone used is between150 and 400 g/liter and the reaction temperature is between 60° and 90°C.
 22. A process according to claim 19 wherein the amount of6-chlorobenzoxazolone used is between 150 and 400 g/liter and thereaction temperature is between 60° and 90° C.